Emco 120 Transformer Wiring

Hey everyone,
I'm in the process of hooking up my new Emco 120P and have a couple of transformer wiring questions. I'm using an American Rotary AD-10 rotary phase converter.

- Do I need a neutral connected from my 220V single phase supply to the transformer? (I don't currently have one.) There is some discussion in the Emco manual about how the machine requires a neutral, but that the transformer will make one. It looks like the previous owner had a neutral connected to the Mp terminal on the far right of the transformer.



there is also some nice discussion of transformer wiring here: http://www.practicalmachinist.com/vb/cnc-machining/emcoturn-14-a-183698/

Thanks!
Jacob

For highly technical reasons, the primaries of three-phase distribution transformers are wired as deltas, whereas the secondaries are usually wired as wyes.

However ...

The "utilization equipment" is supposed to be compatible with either wye or delta, and most commercial or light industrial premises are in fact delta (think: 120/240), for economic reasons, whereas heavy industrial premises are in fact wye (think: 120/208 or 277/480).

Whenever a distribution transformer is delta-wye, you will usually find H1, H2 and H3 for the high side, and X0, X1, X2 and X3 for the low side.

Although the X0 is indeed the neutral, this should not be used as such, unless supplying a single-phase "utilization equipment".

If a three-phase "utilization equipment" actually requires, say, 120 single-phase within the machine, then a control transformer should be incorporated within that machine, and should that 120 be brought outside of that machine for, say, a "convenience outlet", then one side of the 120 should be brought to the machine's frame, thereby creating a "separately derived system".

Pantechnicon,

Couple of suggestions to get some help here.
Put a location on your profile. The thread you linked to is is devoid of diagrams or pictures, because it's old and the reference links are no longer valid. In the discussion there, even the 2 parties had differing transformers, and is likely that you have something different yet.

Scan and post up the manual pages you speak of. Is there a diagram in the manual? Is there a tag or connection diagram on the transformer? Can you show some better photos of the transformer terminal connections? From the photo submitted all we can really see is a 3Φ multitap transformer, can't see the terminal designations or existing connections.

Some info on the machine itself would be helpful too, what is it set up for, voltage and current wise? In other words what is the desired output from the transformer?

SAF Ω

Jacob, this is a very vague thread where we don't know the specs of the machine you'll be winding your transformer with. Also, you can simply use a neutral, even if the machines makes one, it won't be very catastrophic to have two neutrals. I guess if you can read the manual, there will be really useful information related to the winding.

Regards,
Bill D.
http://blog.7pcb.com